1. Field of the Invention
The invention relates in general to a charge pump, and more particularly to differential charge pump.
2. Description of the Related Art
Referring to “A Subpicosecond Jitter PLL for Clock Generation in 1.12-um Digital CMOS” written by Nicola Da Dalt and Christoph Sandner and published in book 38, period 7 of a solid-state device journal in July by IEEE, the journal discloses a conventional charge pump which uses an operational amplifier to generate a feedback control voltage. However, when the charge pump is initialized, it needs another operational amplifier to stabilize a voltage drop between nodes of a charge switch and discharge switch so as to prevent voltage instability due to floating.